One of causes of noise generated in pneumatic tires is cavity resonance sound associated with vibration of the air filled inside a tire. When a tire is rolled, the air inside the tire is vibrated by the vibration of the tread portion due to irregularities of a road surface, which generates this cavity resonance sound.
As means for reducing noise due to the cavity resonance phenomenon, it has been proposed to reduce time during which the air resonates at a single frequency by changing the cross-sectional area of a cavity portion formed between a tire and a rim of a wheel in accordance with a position in the tire circumferential direction (for example, refer to Patent Document 1). Moreover, for achieving a change in the cross-sectional area of the cavity portion, it has been proposed to attach a plurality of objects to the inner surface of a tread portion with a ring-shaped band member (for example, refer to Patent Document 2). By employing such methods, it is possible to easily attach objects providing a change in the cross-sectional area to the inner surface of a tire.
However, when objects formed of, for example, a porous material, such as polyurethane foam, are fixed to a band member by using an adhesive agent or an adhesive tape, the porous material sometimes reacts with a component included in the adhesive agent or the adhesive tape to be decomposed. As a result, the adhesion of the objects is deteriorated. For this reason, the means for fixing the objects to the band member has an advantage that the means facilitates the attachment of the objects to the inner surface of the tire, but is insufficient in terms of the durability. Moreover, the bonding of the objects formed of a porous material to the band member with the adhesive agent has a disadvantage that it takes a long time for the adhesive agent to set.    Patent Document 1: Japanese patent application Kokai publication No. 2001-113902    Patent Document 2: Japanese patent application Kokai publication No. 2003-226104